Gender-based power imbalances continue to place individuals at increased risk for HIV/AIDS throughout sub-Saharan Africa, including Malawi. Research has shown that power in sexual relationships is linked to health in several ways, one of which is through its influence on the use of health services. Voluntary HIV counseling and testing (VCT), an increasingly important prevention service in Malawi, has been inadequately studied with regard to relationship power. Despite widespread access to VCT, uptake of testing is low and for those who do receive VCT, sexual behavior change remains modest at best. I postulate that relationship power is one of the missing pieces of information that could explain HIV testing behavior within couples. The Theory of Gender and Power (TGP) proposes that the economic inequality, control of one partner over the other, and social norms related to gender and sexual behavior can elucidate the behavior of men and women. I will use the TGP to generate hypotheses regarding the interaction between power and HIV testing. This project has three specific aims, with a focus on the third aim. The first aim is to conduct a formative study using focus groups of married and dating men and women to understand the culturally rooted dimensions of power within Malawian couples. The second aim is to explore appropriate quantitative measures of four theorized constructs of sexual relationship power for the Malawi context: dependence, feelings of love and trust, effective partner communication, and experiences of relationship dominance. The third aim is to conduct a quantitative study using measures of power from aim 2 to understand the effects of relationship power on three aspects of HIV testing: use of testing services, disclosure of test results, and how learning one's HIV status influences relationship power after testing. I will utilize high-quality, longitudinal couple data collected through the currently ongoing Tsogolo La Thanzi (TLT) study to explore measures of power and test study hypotheses based on the TGP. I expect that the level of relationship power will determine whether individuals have received a previous HIV test and this association will vary by gender. Disclosure of test results will depend upon the access to wealth and property, power, and the test result. I also anticipate that HIV testing will change relationship power dynamics within couples, however, the directionality of changes will depend upon gender, perceived test result, and actual test result. PUBLIC HEALTH RELEVANCE: New information on key relationship variables that determine health decision-making will generate far- reaching conclusions about couple behavior that can be used to formulate new interpersonal theories on behavior. Not only will this study broaden understandings of the relationship between couple dynamics and HIV testing, it will contribute to the evidentiary basis for individual and couple-based prevention services throughout sub-Saharan Africa. Finally, new measures of relationship power for the Malawi context will provide opportunities to evaluate the effectiveness of public health interventions aimed at improving gender relations within couples.